Hypermedia documents are computer-based documents that contain text and graphics on pages that are connected via navigational links or buttons. Hypermedia documents constitute an alternative to the book that permits nonsequential access to pages. Embedded hypermedia documents are also found in many user interfaces, such as aircraft cockpits, power- and industrial-plant control consoles, information kiosks, automated teller machines, videocassette recorders, and many other systems. In all such instances, the problem of designing a hypermedia document involves two key tasks: assigning information to particular pages, and determining how the pages are linked. These tasks should be done so as to facilitate the efficient traversal of the document by users.
For instance, the multifunction display, MFD, in an aircraft cockpit is a hypermedia document that contains important flight data and controls that cannot fit on the pilot's control panel. A typical MFD contains 20-100 linked pages of information, ideally linked so that the pilot can quickly access the information he needs in a wide variety of normal and abnormal operational situations. Since the information is provided to the pilot on a single CRT display, it is often with difficulty that a designer of MFDs can arrive at appropriate content and efficient linkage of the pages of information presented to the pilot.
In the past, designers have provided such structure and links on an ad hoc basis in which the structure and links are specified manually. The problem with such manual procedures is that they are inordinately time-consuming and often result in grossly non-optimal presentations. For instance, when more than 100 pages of information are to be displayed, it may take several man months to create a prototype hypermedia document for use as a cockpit MFD. Thereafter, the prototype is tested for convenience by the potential users of the system to ascertain the level of convenience provided by the prototype, which may then require iterative refinement and improvement.
Because there are no computer-aided functions that can be applied to the design of such MFDs, there is often no rigorous accounting for the relative importance of information or for flexible ordering of the presentation of information, much less a system for optimizing the document structure.
This problem is also severe not only for cockpit MFD design, but also the design of information kiosks like automated teller machines, ATMs, in which the user must oftentimes page through irrelevant screens to get to the screen containing information that he currently wants. For instance, an individual wishing to check his account balance must typically page through three to four screens to access the information.
Moreover, books are prepared as linear documents in which the paging sequence is fixed. This type of linear format is nonoptimal, especially for texts with multiple intrinsic cross references, because the linear format does not permit the user to be presented with information from different portions of the book in a different order that is both more convenient and that provides the information in a customized manner related to relevance. This and other problems described above are all hypermedia-document-structuring tasks that are addressed by the Subject System.